The 34-year-old actress struck about a close rapport with the 29-year-old actress - who has daughters James, two, and 19-month-old Ines with her husband Ryan Reynolds - when they appeared in Sisterhood of the Travelling Pants together, and she has revealed she is so close to the blonde beauty she has even sampled a taste of her bodily fluid in the past.

Speaking on Watch What Happens Live with Andy Cohen, the House star said: "I've drunk Blake Lively's breast milk."

This news comes after Amber gave the chat show host a bottle filled with her own breast milk to try, which she believes would "technically" contain some of The Shallows star's liquid.

She explained: "So if that went through me, you've technically had Blake's and my breast milk together."

Amber gave the 48-year-old host a taste of her milk because she had guzzled down a "giant" glass of bourbon and then had "two pumping sessions", but feared the liquid would contain alcohol so she avoided passing it on to her two-month-old daughter Marlow, who she has with her husband David Cross.

She explained: "I had a giant glass of bourbon, my first in almost a full year. And then my next two pumping sessions ended up in my husband's mouth, let's be honest.

"He was like, 'I want to try that since the baby can't have it'. He had his first breast milk ... He said it was creamy. He liked it - of course he did!

"Do you want to taste it. I pumped when I got here earlier ... from work. Want me to make you a White Russian?"

And Andy seemed to enjoy the breast milk as he described it as "very sweet".

He said: "It's very sweet. It's sweet. And it's good with a tequila chaser! Wow. Can I have more? That's the closest to a breast I've ever been.